Effect of Gaseous Ammonia on the Health and Welfare of Sheep (Ovis aries) and Cattle (Bos taurus)

Sea transportation of sheep and cattle, exported from Australia to the Middle East, involves extended journeys in compromising conditions including high ambient temperatures, high relative humidity, high stocking rates, the movement of the ship and high ammonia levels. Little is known about the effects of ammonia on livestock on board these vessels, particularly sheep. Two experiments were conducted to investigate the effects of various concentrations of ammonia on the health and welfare of sheep and cattle. In experiment 1, sheep and cattle were held in climate controlled chambers simulating the conditions on board a 12 day (d) journey from Australia to the Middle East. They were exposed to four ammonia concentrations while a comprehensive assessment of behavior, dietary intake, weight change, lung pathology and haematological parameters associated with immunocompetence and stress was conducted. In experiment 2, a choice test Y-maze was established where two groups of sheep were trained to press a lever, one previously exposed to ammonia, to enter the maze based on the presence of a food reward and subsequently the persistence to press the lever once the maze was filled with ammonia was assessed. Ammonia concentrations typical of those on board a livestock vessel had an influence on live weight gain, the time spent standing and panting in the steers and locomotion in the wethers. Results also showed that lacrimation, nasal discharge and coughing increased with ammonia treatment in the steers. There was evidence that ammonia irritated the respiratory surfaces of both wethers and steers with increased macrophage activity and iv neutrophil count. Results showed a partial aversion of sheep entering a chamber of 45 parts per million (ppm) atmospheric ammonia, however it was also shown that previous exposure to ammonia did not influence the aversion to entering the chamber for a food reward. Ammonia concentrations on board livestock vessels reach concentrations which inflict changes in the livestock's behavioral and physiological well being. These concentrations however, may not be prevalent enough to cause concern. Other behavioral changes directly attributed to increases in wet and dry bulb temperature, may be of a concern to the animals’ welfare. Even so, both atmospheric conditions may be managed on board vessels dually using air ventilation practices. Given that results showed that ammonia had an effect on live weight gain, the causation of this should be further investigated as it could benefit the industry's profitability.